HW9_skeleton

9.2

• 1. decreases
• 2. false
• 3. a
• 4. true
• 5. false
• 6. robust
• 1. 1.316

  2. 1.697

  3. -2.552

  4. 1.725

• 1. 2.205

  2. 1.309

  3. -1.943

  4. 2.120

• 13. X-bar=21, E=3
• 14. X-bar=25, E=5
• 1. LB=103.656, UB=112.344

  2. LB=104.5, UB=115.6. Decreased sample size=increased margin of error

  3. LB=104.5, UB=111.4. Decreased level of confidence=decreased margin of error

  4. No because sample size was too small

• 1. Flawed because the interpretation imples that the population mean varies, as opposed to the interval

  2. Correct

  3. Flawed because the interpretation implies info about individulous instead of the mean

  4. Flawed because the interpretation should be about the mean hours worked by American adults not adults from idaho.

• 29. LB=317.6, UB=394.6. We are 95% confident that the mean number of licks is between 317.6 and 394.6.
• 30. LB=12.04919, UB=14.75081. We are 99% confident that the mean number of books that americans read either all or part of during the preceding year is between 12.05 and 14.75.

9.3

• 1. False
• 2. true
• 3. false
• 4. true
• 5. x^2 .95=10.10.117, x^2 .05=30.144
• 1. LB=7.94, UB=23.66

  2. LB=8.59, UB=20.63. The width of the interval decreases

  3. LB=6.61, UB=31.36. The width of the interval increases

• 11. LB=.226, UB=.542. We are 95% confident that the population st. dev. of the pH of rainwater in Tucker County, WV is between .226 and .542